Interpretive Summary: Paclitaxel is a novel compound present in small amounts in all parts of (yew) plants, and its success as a cancer treatment has spurred interest in alternative sources for the drug. Needles from yew plants have been successfully used to extract a precursor required to produce paclitaxel by a semi-synthetic process, but the published procedures employ large amounts of hazardous solvents for extraction. Our goal was to find a more efficient, economical, and environmentally sensitive method to extract paclitaxel and related taxanes from needles. We have developed an extraction method which can be applied to either fresh or dried needles, using simple nonhazardous solvents, and yields a highly enriched taxane fraction which can be further purified. This research was funded via a grant from the National Research Initiative (USDA/CSRS 93-37103-9269).

Technical Abstract:
Leaves of Taxus x media and Taxus brevifolia were examined for their potential use as a source of paclitaxel and related taxoids. Various solvent systems were compared for their efficacy in the extraction of paclitaxel, as well as the extraction of contaminating residue. A method of extraction has been developed that enriches paclitaxel by over 500-fold using only potable solvents in combination with solid phase extraction, thus avoiding the use of chlorinated hydrocarbon solvent systems. This solvent system can be used on fresh leaf material, eliminating the need for drying material before extraction, and preventing degradation of the taxoids during the drying process. Using these methods, paclitaxel constituted 0.01 to 0.02% of the dry weight of the leaf tissue from Taxus x media, and 0.04% from dried needles of Taxus brevifolia.